FARGO -What troubled U.S. District Judge Ralph R. Erickson most wasn't that Silas Lee McHenry Jr. stole $1.2 million from the federal government.

It was that the Grand Forks man did so over the course of nearly three decades, consciously choosing each month for 320 months to accept his deceased father's federal pension checks and cash in on the bankroll.

"He showed a commitment to criminal conduct that is rare," Erickson said during McHenry's sentencing hearing Monday in Fargo. "At no point did the light go on and say, 'It's time to end this.' "

McHenry will serve three years and eight months in prison for his theft, which the Office of Personnel Management calls the largest scheme of its kind ever encountered.

After Silas McHenry Sr. died in 1983, Silas Jr. failed to notify OPM that his father had died and continued to accept the monthly pension checks in his father's name.

Between April 1983 and November 2009, the OPM sent the checks, believing McHenry Sr. was still alive. On at least four separate occasions over the 26-year period, OPM officials requested verification of the elder McHenry's status, and each time, his son lied to the government and masked his father's death.

McHenry's attorney, Joel Larson, said McHenry was abused by his father and initially accepted the checks as retaliation.

"He felt he was entitled to it," Larson said. "It doesn't make it right, but that's what he used to justify his actions."

Sentencing guidelines called for the sentence of between 41 and 51 months in prison. Assistant U.S. Attorney Scott Schneider sought the maximum penalty, while Larson asked for only probation as a show of leniency for an otherwise law-abiding citizen.

"I'm afraid the reasons I did what I did have faded after 26 years," McHenry said before his sentence was handed down.

Erickson decided on a sentence in the middle of the guideline range, saying he wanted to convey the seriousness of the "egregious offense."

"It's always a danger when you look at stealing from the government, that people aren't convinced they're taking from their neighbors, but that's what it is," Erickson said.

McHenry will have to pay back the $1.2 million he stole, but government officials don't expect that to happen. The U.S. government has so far recovered $4,000 in cash, a vehicle worth about $21,000 and real estate McHenry owned in East Grand Forks, Minn., Schneider said.